/*
 * Copyright 2023 ABSA Group Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package za.co.absa.spline.commons.lang

import scala.collection.mutable

/**
  * Stackable abstract converter between two arbitrary types
  */
trait Converter {
  type From
  type To

  final def apply(arg: From): To = convert(arg)

  def convert(arg: From): To
}

/**
  * Memoized converter
  */
trait CachingConverter extends Converter {
  private val cache = mutable.LinkedHashMap.empty[Key, To]

  def values: Seq[To] = cache.values.toSeq

  protected type Key = Any
  protected def keyOf(x: From): Key = x

  abstract override def convert(arg: From): To =
    cache.getOrElseUpdate(
      keyOf(arg),
      super.convert(arg)
    )
}
